There aren’t too many creatures that give people the willies more than worms do. Charles Darwin called these organisms the “ploughs of the earth,” and at any given time there are up to over a million earthworms in a single acre of land. These slimy, wriggling staples of fishermen everywhere inspire revulsion and loathing to many, and although they are crucial to our ecology, they have mostly remained hated and underappreciated.

The image that many have of worms is of a small creature, maybe as long as one’s finger or hand, and for some this is quite big enough. Yet can you imagine a worm as long as your arm? How about one as long as your leg? Even longer still? That’s a mighty big fishhook.

In Japan, the longest known species of worm is known as the Seibold earthworm (Pheretima sieboldi), which reaches typical lengths of around 25 ~ 28 cm (9.8 ~ 11 inches), although specimens of around 40cm (about 16 inches) long or over have also reportedly been found on occasion. Some areas in Nara prefecture, as well as the southern Ryukyu islands have reliably documented worms from 40 to 50 cm (16 ~ 19.6 inches) long. These are big worms to be sure, but are there even more massive worms lurking in the earth in Japan?
There have long been tales of enormous earthworms surfacing from time to time in various areas of Japan. One of the hotspots for such accounts is Hyogo prefecture, on Honshu Island, which has many historical accounts of worms in excess of 1.5 meters (5 feet) long. One such account dates from the year 1712, in what was then known as Tamba province (now part of Hyogo prefecture). The account describes a huge landslide that occurred in a village, after which 2 giant earthworms were found in the debris. One of these worms measured 1.5 meters (5 feet) in length, while the other was larger still, at 3 meters (10 feet) long. Another landslide that occurred in the same general vicinity allegedly unearthed a 4.5 meter (15 feet) long worm. A more modern report from Mikata-gun, which is located in the mountains of Hyogo prefecture, dates from 1996 when a farmer uncovered an earthworm 1 meter (3.3 feet) long and 2cm (0.8 inches) thick while planting a tree on his rural property. It was the first time the surprised farmer had ever encountered such a large worm in all his years in the area.

Giant worms have been reported from other parts of Japan as well. In Okayama prefecture, one woman claimed to have seen a worm 3 meters (10 feet) long in a field that was being tilled. The worm had apparently been disturbed by the farming activity. Another farmer in the same prefecture brought up a still thrashing piece of a worm that had been hacked off during farm work. The piece is estimated to have come from a worm 3.5 to 4 meters (11.5 to 13 feet) long. The rest of the worm could not be located.

Perhaps the strangest report comes from Fukuoka prefecture, on the island of Kyushu. In 1997, a Mr. Ou Sato and his friend spotted something odd near the side of a river that they at first took to be a hock of ham someone had discarded. Thinking this to be a bit odd, the two approached to get a better look. On closer inspection, they found the mysterious object to be a tubular piece of flesh, 30 cm (1 foot) long and 20 cm (8 inches) in diameter, with thin, glistening wet skin. There were clear grooves encircling it like those of an earthworm’s segments, and the color was described as brown like “a bursting sausage.” There was no evidence of the object possessing bones of any kind. Both ends of the curious piece were ragged and torn, leading the two men to estimate that it was obviously a piece from the carcass of a much larger animal. The witnesses’ impression was that it originated from a gigantic earthworm, which they estimated the full length as being perhaps 10 meters (33 feet) or more. Unfortunately, due to the slimy and slightly decomposing nature of the find, they left it where it lay.

How feasible is it that worms of these sizes could be living in Japan? Although the lengths we are talking about here may seem to be firmly in the realm of myth and fantasy, the dimensions are actually comparable to a few known species of worm in nature that reach truly enormous proportions. The various species of giant worm have a wide distribution, and are found in far flung places all over the world.
Perhaps the largest overall known species is the giant Gippsland earthworm (Megascolides australis) ~ seen above, which is found only in the Bass River valley of South Gippsland in Victoria, Australia. These huge worms regularly reach sizes of 3 meters (10 feet), and the longest specimen on record was measured at 4 meters (14 feet) long. These rare earthworms are so large that it is possible to hear the gurgling sound of their movement through the earth when they are disturbed.

In neighboring New Zealand, there is another large worm known as the North Auckland worm (Spencerilla gigantean), which reaches a length of 1.4 meters (4.5 feet). These worms have the added surprising, some might even say creepy, feature of glowing in the dark. By some accounts, the light the worms emit is said to be bright enough to read by.

The United States has its own giant worm as well. The Palouse earthworm (Driloleirus americanus) of the northwest can reach lengths of up to 1 meter (around 1.3 feet) long, perhaps even more. These worms have a historic range throughout the Palouse Prairie, which stretches out over southeastern Washington state and northern Idaho, and is sometimes even considered to encompass parts of Oregon and northwestern Montana as well. The Palouse earthworm is a striking white color, and is said to be able to spit defensively at those that provoke it. These large worms were thought to be extinct in the late 1980s however in the spring of 2005 a University of Idaho graduate student located a specimen by accident during a dig. Several other specimens or parts of specimens have been reported since.

Europe also has its giant worms. The Black Forest region of Germany is home to a 2 foot long worm known as the Giant Badish earthworm (Lumbricus badensis). Sardinia, Corsica, Italy, Sicily, and southern France are home to a species of the earthworm family Hormogaster that can get as long as 75cm (2.5 feet).
Another of the largest known species is the South African giant worm (Microchaetus rappi) ~ seen above. These worms normally grow to around 1.8 meters (6 feet) in length, but there is evidence that they can get much larger. In 1967, a South African worm was found by the side of a road in William’s Town that measured an incredible 6.7 meters (22 feet) long. This specimen remains the longest earthworm ever confirmed.

Is something like this living in Japan?

The sizes given in most Japanese giant worm reports are within the realm of possibility considering the known species of giant earthworms found in other parts of the world. There is no real reason in particular to dismiss the possibility of earthworms corresponding to these sizes in Japan. Furthermore, the very nature of the animals could help keep them hidden from human view, which could account for their elusiveness and the rarity of reports. Depending on the species, some earthworms can burrow quite deep underground, and may rarely if ever come to the surface. Burrow systems as deep as 6 meters or more are not uncommon for some species. This would help to explain how a creature this large could go for some time with little contact with humans, thus remaining unverified. It is interesting to note that several of the Japanese giant earthworm cases were reported in conjunction to some sort of disturbance of the ground, such as a landslide or digging up of the earth. This detail seems consistent with what we could expect of a rarely seen type of earthworm lurking underground in its burrow most of the time.

The Fukuoka giant worm carcass account is a bit more difficult to explain. The estimated length, while far beyond that of any known species of worm, is perhaps plausible for some extremely large unknown species, however the 20cm (8 inch) diameter is another matter. Length is not necessarily a huge burden for an earthworm, but body thickness is. These are burrowing organisms that rely on being able to move as easily as possible through the soil. There are no unnecessary appendages or protuberances on earthworms, and their bodies are geared towards burrowing with as little encumbrance and as much efficiency as possible. For this reason, you will find that even the largest known earthworms are not particularly thick in relation to their considerable body length. For instance, the giant Australian Gippsland earthworm for all of its size is still only 2cm (0.8 inches) in diameter at its thickest point. Likewise, the giant Palouse earthworm of the United States is typically only a half an inch in diameter. Even in the case of the longest known specimen of earthworm ever recorded, the 22 foot long South African worm mentioned earlier, the diameter was still only around 2 cm. If a worm was any thicker than this, it would find it increasingly more difficult and less energy efficient to burrow through the ground.

In earthworms, the overwhelming message we get so far concerning their adaptations to a burrowing lifestyle is that length can be extended to an unknown degree, but thickness is limited. So what are we to make of an estimate of a 20 cm (8 inch) diameter in the Fukuoka giant worm account? It just does not seem particularly likely that a burrowing worm would get quite that thick, considering what we see in earthworms that we know of. If the carcass was indeed part of a worm and consistent with the ratio of length to diameter found in known worms, it would have to have been a colossal beast of truly prodigious proportions indeed.

Perhaps it is worth considering that what was seen in Fukuoka was not a worm at all? The site where the remains were found was near a river, close to the water, which leads one to speculate whether some sort of aquatic creature could be the culprit. While there are aquatic freshwater worms, they are typically quite small and nowhere near the sizes being reported here. It has been speculated that an eel or even a part of a dead Japanese giant salamander could have been the culprit, but it is hard to reconcile those explanations with the descriptions given since it is difficult to imagine what kind of creature would leave a tubular piece with no bones and signs of worm anatomy such as the grooves or segments mentioned. Could we be dealing with some type of unknown aquatic invertebrate, perhaps one that made its way up the river from the sea? This may explain the lack of other reports of such thick worms, as well as the death of the animal in question.

Some in Japan have speculated that the carcass could have been part of a caecilian, a type of burrowing, snake-like amphibian.
In his book In Search of Prehistoric Animals, the cryptozoologist Karl Shuker proposed just such a theory when investigating the Minhocão, a giant worm-like cryptid from South America-illustrated above. Shuker proposed that this creature could have been some type of enormous caecilian, These amphibians have limbless, segmented bodies that offer a close match to the appearance of earthworms. Shuker reasoned that since these creatures are so similar looking and burrow in a manner reminiscent of earthworms, then perhaps a large, undocumented species of caecilian could be behind the reports of the Minhocão. Could the giant worm carcass found in Fukuoka also have been that of some type of giant caecilian?
Despite the lack of bones reported, caecilians would certainly account for the general appearance of the Fukuoka carcass. The segments would be perfectly mistakable for those of an earthworm. While caecilians do clearly have heads, since only a portion of the creature’s body was found, it seems reasonable to assume that would not be much of a problem in this case. However, again we are dealing with a burrowing creature unlikely to get too thick. As is the case with earthworms, caecilians do not get very wide in relation to their body length. An even bigger argument against a caecilian would be that they are not known to live in Japan at all. The closest we get with caecilians in Asia is the family Ichthyophiidae, or Asiatic tailed caecilians native to Southeast Asia. Of these, the most northern ranging species is Ichthyophis sikkimensis of northern India. If a caecilian is behind any of the giant worm reports in Japan, it would be a new creature previously unrepresented in the country, as well as absolutely enormous.

Other possibilities include some sort of giant slug, however the presence of apparent segments seems to be at odds with a slug’s overall smooth skin.

Some sort of gigantic millipede is also perhaps worth considering, however there were no legs reported on the carcass and the size would suggest a millipede unlike anything we now know of, perhaps beyond the physical limits of size for such a creature.

When looking at these giant worm reports, one almost gets the feeling that we may even be looking at two different types of cryptid, giant worms in the case of reports like the Hyogo accounts, and perhaps something else with the Fukuoka carcass. One wonders what we would have discovered if the whole animal had been found in Fukuoka, or if the witnesses had recovered the specimen. As it is, we will likely never know.

Is there an unknown species of giant worm in Japan? There are currently around 6,000 species of earthworm known worldwide, including some of truly enormous proportions. It seems reasonable to think that more will be discovered as we dig and till our way through remote patches of earth. Perhaps Japan is where they next giant species will be uncovered.

In parting, let us consider the possibilities. Humans are exploring the oceans, rainforests, and other frontiers of the world, but what about into the world? What lies in wait for us wrapped deep in its burrow beneath the earth? It is clear that for some cryptids one need not look out to the forests, across seas, or up overhead, but rather down at the ground beneath our own feet.

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About Loren ColemanLoren Coleman is one of the world’s leading cryptozoologists, some say “the” leading. Certainly, he is acknowledged as the current living American researcher and writer who has most popularized cryptozoology in the late 20th and early 21st centuries.
Starting his fieldwork and investigations in 1960, after traveling and trekking extensively in pursuit of cryptozoological mysteries, Coleman began writing to share his experiences in 1969. An honorary member of Ivan T. Sanderson’s Society for the Investigation of the Unexplained in the 1970s, Coleman has been bestowed with similar honorary memberships of the North Idaho College Cryptozoology Club in 1983, and in subsequent years, that of the British Columbia Scientific Cryptozoology Club, CryptoSafari International, and other international organizations. He was also a Life Member and Benefactor of the International Society of Cryptozoology (now-defunct).
Loren Coleman’s daily blog, as a member of the Cryptomundo Team, served as an ongoing avenue of communication for the ever-growing body of cryptozoo news from 2005 through 2013.

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7 Responses to “Giant Worms of Japan”

Once again, a fascinating and wonderful post! Curious indeed…I do have to wonder about that thing that was found. Too bad it couldn’t have been sampled for genetic analysis. Oh well. Still, very interesting.

“In neighboring New Zealand, there is another large worm known as the North Auckland worm… which reaches a length of … 4.5 feet. These worms have the added … feature of glowing in the dark. By some accounts, the light the worms emit is said to be bright enough to read by.”

Ok, which Kiwis out there want to pitch in and help me make Loren the world’s most exotic (and disgusting) book light for Christmas?

A piece of intestine is a novel idea, but a section that is 8 inches in diameter? I suppose it is a possibility, but I wonder what kind of animal such a large piece of intestine would have come from and how it might have ended up detached and left by the side of a river like that. That is certainly an interesting idea, though.

In regards to what animal such an intestine piece could have come from, my first guess was cow. However, I checked and the diameter of cow small intestine is 2.5″ -4″ (definitely right up there in my top 10 strangest personal Google searches). However, I did find out that in regards to horses, “the large colon [has] a diameter of 8 to 10 inches [and] is 10 to 12 feet long”. Looking at a few drawings seemed to show the same segmentation and general grossness of the worm description. I’m not arguing that’s what it is, but the author does note that even when worms grow very large they continue to maintain a small diameter, so I was just brainstorming as to what non-worm explanation the observation could have, and “misidentified lightpost” was already taken. I’m not sure that the color matches, and invoking decay would only be speculation. Speaking of speculation, I’m not sure how the original observers estimated the original creature may have been 33 feet long when they only observed 1 foot of remains, unless they were basing it on the diameter.

“…and how it might have ended up detached and left by the side of a river like that.” As to detachment, I’m sure there’s lots of ways, but any one would be speculation, especially without knowing the area. This could have been downstream from a butcher shop for all we know. But I’d say it’s a good possibility that whatever was found wasn’t left by the side of the river but washed down the river, especially as the author notes there was some decomposition. Hmm… actually, if it had been in the water, whatever it is (intestine, worm, etc.) could have swelled considerably. When I was a youngster, my brother and I had some pet salamanders, one of whom decided it would no longer eat store-bought salamander food anymore. My brother took to catching worms at night and feeding them to the salamander. I’ll say from personal experience that a piece of worm left in water for less than 24 hours does indeed swell up. Maybe it was a giant worm after all, one that also plumped up from water absorption! Just another thought.

By the way, let me commend you Mr. Swancer on an excellently written piece, thoroughly researched and brimming with useful information. It raised all sorts of thoughtful possibilities without straying from the facts and made several intriguing connections between disparate cases and places. Oh, and the pictures alone are enough to give me nightmares. Thank you for one of the most well-researched and thought-provoking articles on any subject matter that I’ve read in the last few months.

Great post as always, Mystery_Man.
I agree with you—what kind of an animal has THAT big of an intestine??? Not something I would want to go anywhere near, that’s for sure. And I don’t like worms overall. Yeech. They may be “necessary” creatures, but they’re not “for me.”

Alcalde- Yes, it is certainly true that from what we know of worms, the diameter is unlikely to get very thick. 8 inches is well beyond what we should expect from even a very long worm.

The author did indeed say that, I should know- he’s me! I do appreciate the non-worm possibilities you are offering. To be honest, if I had thought of the intestine hypothesis myself, I would have included that in this article. It is an interesting bit of speculation, and probably at least as likely as a worm 8 inches in diameter. The grossness factor also seems about right, but I agree the color is perhaps not a good match. Very good input on your part anyway, and I thank you for doing the research on intestine diameters of various species. You are braver than I. I dread to think what Google images turns up on that.

I still wonder what a huge piece of horse intestine would be doing torn off and laying discarded by the side of a river, but you are right, without knowing the area, it is indeed hard to say. I don’t have a lot of information in that regard except to say that apparently it was a fairly rural area, which leads me to think a butcher shop in the immediate vicinity is unlikely, however you never know. It certainly seems worth considering as a possibility in a bizarre case like this, where there are so many unanswered questions. All we can do is speculate. Nothing wrong with throwing these ideas out there, and I’m glad you did.

Considering the apparently decayed state of the carcass piece, and the proximity to the river, I too considered the possibility of bloating. It would help to explain the size of the thing, and is well within the realm of possibilities. We all know that bloated, decaying carcasses can exhibit bizarre appearances, and an organ like an intestine would be likely to do so as well.

To clarify about the length estimate, the two who found the piece based that purely on the hefty diameter of the thing and the assumption that it was indeed a section of worm. I would not lend too much scientific credibility to that estimate, as it seems to have just been a guess posited by those that found it.

Whatever it was, it certainly was weird. I appreciate your input on the matter.

I also wanted to let you know that your words of praise for this article were very much appreciated. They really meant a lot to me, so thank you. I really do try to put my all into researching and putting these articles together so knowing they are enjoyed makes it all worth it.

Cryptidsrus- Yeah, I’ve never had too much of a problem with worms, but I certainly think I can understand the aversion some people feel towards them. They sure aren’t the most charismatic organisms.